Modern portable electronic devices are demanding increasing amounts of electrical power and chemical batteries are often the performance bottleneck for such devices. Wireless products, such as personal digital assistants, mobile phones, entertainment devices, and next generation laptops in particular have a great demand for sustained power. For long-term portable operations, fuel cells are an attractive solution. Fuel cells, like batteries, efficiently convert chemical energy into electricity, but have additional advantages, such as higher energy density and the capability for instant refuelling. Fuel cells are typically fuelled by hydrogen gas, but there are technological challenges in storing and delivering hydrogen gas to the fuel cells in a cost effective and efficient manner. One particular challenge is to provide a fuel supply that is inexpensive, safe, light and compact enough to be readily portable yet store enough hydrogen to provide a useful amount of fuel to the fuel cell. State of the art means for storing hydrogen include metal hydride canisters to store hydrogen at relatively low pressures, and pressure tanks to store compressed hydrogen at elevated pressures. Both approaches have drawbacks; for example, metal hydride storage is relatively safe but has a low energy density to weight ratio, and compressed hydrogen storage can have a high energy density to weight ratio but requires high strength and expensive containment solutions.
Research has been conducted into using liquid methanol as a fuel and designing a “direct methanol” fuel cell that electrochemically produces electricity directly from methanol; however, significant technological challenges exist such as preventing methanol cross-over through the electrolyte membrane, and preventing catalyst poisoning by the methanol fuel.
Other efforts have been directed at generating hydrogen gas from a hydrogen-containing fuel solution such as sodium borohydride. In such approaches, the fuel solution is exposed to a catalyst to facilitate the production of hydrogen gas. While this approach is promising, technological challenges exist in containing the caustic fuel solution and preventing leakage, especially when the portable fuel cell system will be used in close proximity to humans.